Balanced carbon pile



July 8, 1958 A. B. ESSEX ETAL BALANCED CARBON FILE 2 Sheets-Sheet 1Filed Nov. 23, 1956 S min w TERN m mfikm 0 mix m if m m7: Aam M M July8, 1958 A. B. ESSEX EI'AL 2,842,646

BALANCED CARBON PILE Filed Nov. 25, 1956 2 Sheets-Sheet 2 ATTORNEYljnited States l a BALANCED CARBON PILE Alois B. Essex, Glendale, andElmer E, Garrett, Freeport, N. Y., and Henry F. McKenney, Weston, Massassignors to Sperry Rand Corporation, Ford instrument Company Division,Long Island City, N. Y., a corporation of Delaware Application November23, 1956, Serial No. 523,845 3 Claims. (Cl. Till-51) This inventionrelates. to variable resistance devicesof the carbon pile type which areespecially adapted for use in airplanes and guided missles which aresubjected to vibrations and rapid accelerations and decelerations.

Carbon pile rheostats of this character generally corn: rise a pile ofcarbon discs which are held under compression' by the action of a springdiaphragm, and a solenoid which is operative when energized torelievethe spring pressure upon the pile of discs and thus control the pileresistance. The spring diaphragm has an armature rigidly secured theretothrough which the solenoid acts to relieve the pressure exerted by thespring diaphragm upon the pile of disCS, aI1d adjusting means areprovided by which the maximum pressure exerted by the diaphragm upon thepile of discs-may beregulated as desired. When such a resistance deviceis axially accelerated in one direction the armature, due to inertia,reacts to increase the pressure upon the carbon-piles and therebydecrease the resistance of the pile; and when the device is acceleratedin the opposite direction the armature reacts to decrease the pressureupon the carbon pile and thereby increase the resistance of the pile,and the same reactions occur during deceleration. This inherentcharacteristic of carbon pile resistance devices of this characterrenders them objectionable for uses wherein they are subjected to axialvibrations and accelerations.

It is therefore the principal object of this invention to provide meansin a carbon pile resistance device of the aforesaid character by whichthe vibration and acceleration effects upon the carbon pile arecounteracted whereby the pile resistance is maintained constant underall conditions of use. This may be accomplished by providing two similarcarbon pile rheostats disposed back to back in axial alignment with thecarbon piles electrically connected in series and the armature endsthereof pointing in opposite directions. With this arrangement underacceleration the resistance of one carbon pile will be increased and theresistance of the other carbon pile will be proportionately decreasedwhereby the combined resistance of the two carbon piles will always bemaintained constant.

The principal object of the invention having been stated other and morespecific objects of the invention will be apparent from the followingspecification and the accompanying drawings forming a part thereofwherein,

Fig. l is a central longitudinal section illustrating one form of theinvention in which two similar carbon pile resistance units are disposedback to back in axial alignment with the carbon piles electricallyconnected in series and the armature ends thereof pointing in oppositedirections; and

Fig. 2 is a view similar to Fig. l of a slightly modified form of theinvention in which two opposed oppositely pointing carbon piles areutilized.

The two forms of the invention shown in the drawings will now bespecifically described in detail with the use of reference numerals, thesame numerals being applied ice to like parts in the diiferent forms ofthe invention shown. Referring first to Fig. l of the drawings thenumeral 1 indicates generally a variable resistance mechanism whichcomprises two similar conventional carbon pile variable resistance units2 and 3 which are bolted together back to back in axial alignment with aseparating-plate 4 of insulation thcrebetween. Each of the units 2 and'3comprises a casing 5 provided with heat dissipating fins 6. A pile 7 ofcarbon discs is mounted in an open ended tube and which is disposed in alongitudinally extending axial bore 9, in the casing 5, whichcommunicates at the inner end thereof with an enlarged annular chamber10 at one end of the casing 5. A spring diaphragm 11', which is suitablysecured in fixed position in the chamber 19 has secured to one sidethereof a button 12 which is adapted toengage one end of the carbon pile7 and to the other side thereof an armature 1-3 which coacts with asolenoid 14 which is also secured in fixed position in the chamber 10.The carbon discs in the pile 7 are held under compression by the springdiaphragm 11 acting through the button 12. and the pressure exerted bythe diaphragm 11 upon the carbon pile 7 is regulated by an adjustingscrew 15 which engages the opposite end of the carbon pile and iscarried by a removable plate 16 which closes the outer end of the bore9. The solenoid 14 is of conventional construction and comprises thewinding 17 and the core 18 which is carried by the closure plate 19, ofthe chamber it in axial alignment withthe diaphragm i1 and carbon pile7. When thesolenoid 141's energized the core 18 attracts the armature 13which re.- duces the compression of the pile 7 and thereby increases theresistance of the pile 7 to the flow of current therethrough. The carbonpiles '7 in the units 2 and 3 are electrically connected together inseries as indicated at 20, with the armature or solenoid ends of the twopiles facing in opposite directions. In operation either one or both ofthe solenoids 14 may be energized to increase the resistance to the flowof current through the two carbon piles. When the resistance mechanism 1is accelerated to the right, as shown in Fig. 1, the armature 13 in theunit 2, due to inertia, will react to decrease the pressure upon thecarbon pile in the unit 2; and at the same time the armature 13 in theunit 3 will react to proportionately increase the pressure exerted uponthe carbon pile 7 in the unit 3. The decreasing of the compressivepressure upon the carbon pile 7 in the unit 2 will increase theresistance thereof to the flow of current; and the increasing of thecompressive pressure upon the carbon pile 7 in the unit 3 willproportionately decrease the resistance thereof to the flow of current.Conversely when the mechanism 1 is accelerated to the left as shown inFig. l the resistance of the carbon pile 7 in the unit 2 will bedecreased and the resistance of the carbon pile 7 in the unit 3 will beproportionately increased. Obviously the armatures 13 in the units 2 and3 will react in a like manner during deceleration of the mechanism 1.The combined resistance of the two carbon piles will therefore always bemaintained constant during both acceleration and deceleration of themechanism 1.

In Fig. 2 a slightly modified form of the invention shown in Fig. 1 isdisclosed. In this form of the invention the solenoid 14 in the unit 3is omitted. Otherwise the two forms are identical. in this form of theinvention the compressive pressure upon the carbon pile 7 in the unit 3is set by the adjusting screw 15 for the minimum resistance desired andonly the pressure upon the carbon pile 7 in the unit 2 is decreased bythe action of the solenoid 14 to increase the combined resistance of thetwo carbon piles. During acceleration and deceleration of this form ofthe invention the two armatures 13 will react upon the two carbon piles7 in the same manner as described in connection with Fig. 1, and therebymaintain the combined resistance of the two carbon piles constant duringboth acceleration and deceleration.

From the foregoing it will be apparent to those skilled in this art thatwe have provided very simple and efiicient means for accomplishing theobjects of the invention; and although the solenoid is shown anddescribed herein as operative when energized to decrease the compressionupon the carbon pile and thereby increase the resistance thereof, it isto be understood that the invention contemplates thev reverse action ofthe solenoid wherein the solenoid is operative when energized toincrease the compressive pressure upon the carbon pile and therebydecrease the resistance thereof. 1 And it is to be further understoodthat we are not limited to the specific constructions shown anddescribed herein as various modifications may be made therein within thespirit of the invention and the scope of the appended claims.

What is claimed is:

1. A variable resistance mechanism or" the character describedcomprising two opposed oppositely facing axially aligned carbon pilessecured in fixed spaced relation to each other, spring diaphragm meansby which said carbon piles are held under compression disposed betweenthe opposed ends of said carbon piles, solenoid means operative whenenergized to decrease the pressure exerted by said spring diaphragmmeans upon one of said carbon piles, each of said carbon piles beingoperative to counteract the acceleration effects upon the other of saidcarbon piles during axial acceleration of said variable resistancemechanism.

2. A variable resistance mechanism of the character described comprisingtwo similar variable resistance units each of which comprises a carbonpile, a spring diaphragm 'by which said carbon pile is held undercompression, an

armature'secured to said diaphragm, a solenoid operative when energizedto attract said armature and thereby decrease the compressive forceexerted by said diaphragm upon said carbon pile, said units beingdisposed in axial alignment with each other with the solenoid ends ofthe carbon piles thereof facing in opposite directions, whereby each ofsaid units counteract the acceleration etlfects upon the other of saidunits during axial acceleration of said variable resistance mechanism.

3. A variable resistance mechanism of the character described comprisingtwo opposed oppositely facing axially aligned carbon piles disposed infixed spaced relation to each other, a spring diaphragm disposed betweenthe opposed ends of said carbon piles by which one of said carbon pilesis held under compression, an armature secured to said diaphragm inaxial alignment with said carbon piles, a second spring diaphragmdisposed between the opposed ends of said carbon piles by which theother of said carbon piles is held under compression, a counterbalancingweight secured to said second spring diaphragm in axial alignment withsaid carbon piles and said armature, a solenoid operative when energizedto attract said armature and thereby decrease the compressive forceexerted by said spring diaphragm upon the said one of said carbon piles,said armature and said counter- References Cited in the file of thispatent UNITED STATES PATENTS Turbayne Oct. 19, 1920 Austin Feb. 5, 1946

